The invention discloses a heat source control method and a heat source control system for an absorption refrigerator. The heat source control method comprises the following steps: acquiring temperature T inside the refrigerator; if the temperature T is greater than preset high temperature, controlling a heating element to heat continuously; if the temperature T is within a preset cooling range, controlling the heating element to heat periodically; if the temperature T is within a preset temperature keeping range, controlling the heating element to heat periodically. As the heating duty cycle of the heating element is controlled according to the temperature inside the refrigerator and the preset temperature range, energy consumption of the refrigerator can be reduced, the cooling speed of the refrigerator can be increased, and the temperature inside the refrigerator is relatively uniform and small in fluctuation range.